法国蒙彼利埃大学F. Teppe团队在研究中取得进展。他们研究了二维狄拉克费米子的太赫兹回旋发射。相关论文于2023年1月9日发表在《自然—光子学》杂志上。

在这项工作中，研究组实验证明了在这样的HgTe量子阱中狄拉克费米子的朗道发射，其中发射可由磁场和载流子浓度调节。因此，有望实现基于磁场和栅极电压可调谐的太赫兹朗道激光器。

自从石墨烯出现以来，课题组已经看到了关于实现太赫兹频率范围内可调谐的朗道激光器的几个建议。他们希望朗道能级与狄拉克费米子之间的非等距能抑制有害的非辐射俄歇复合。不幸的是，即使有这种非等距，在朗道量子化的石墨烯中仍然存在一个不利的非辐射过程，到目前为止还没有狄拉克费米子的回旋发射的报道。

消除最后这一非辐射过程的一种方法是通过在线性带结构中打开一个小间隙来充分修改朗道能级的色散。接近拓扑相变的HgTe量子阱正是这种缺口类石墨烯材料。

附：英文原文

Title: Terahertz cyclotron emission from two-dimensional Dirac fermions

Author: Gebert, S., Consejo, C., Krishtopenko, S. S., Ruffenach, S., Szola, M., Torres, J., Bray, C., Jouault, B., Orlita, M., Baudry, X., Ballet, P., Morozov, S. V., Gavrilenko, V. I., Mikhailov, N. N., Dvoretskii, S. A., Teppe, F.

Issue&Volume: 2023-01-09

Abstract: Since the emergence of graphene, we have seen several proposals for the realization of Landau lasers tunable over the terahertz frequency range. The hope was that the non-equidistance of the Landau levels from Dirac fermions would suppress the harmful non-radiative Auger recombination. Unfortunately, even with this non-equidistance, an unfavourable non-radiative process persists in Landau-quantized graphene, and so far no cyclotron emission from Dirac fermions has been reported. One way to eliminate this last non-radiative process is to sufficiently modify the dispersion of the Landau levels by opening a small gap in the linear band structure. HgTe quantum wells close to the topological phase transition are a proven example of such gapped graphene-like materials. In this work we experimentally demonstrate Landau emission from Dirac fermions in such HgTe quantum wells, where the emission is tunable by both the magnetic field and the carrier concentration. Consequently, these results represent an advance in the realization of terahertz Landau lasers tunable by a magnetic field and gate voltage.

DOI: 10.1038/s41566-022-01129-1

Source: https://www.nature.com/articles/s41566-022-01129-1